1. Technical Field
The present invention relates to a light source device and a projector.
2. Related Art
A typical projector includes a light source device which has an arc tube provided with a light emission portion where a pair of electrodes is accommodated, and a reflection mirror for reflecting light emitted from the light emission portion.
According to this type of light source device, cooling air needs to be supplied to the upper part of the light emission portion to elongate the life of the arc tube.
For satisfying this requirement, such a technology has been proposed which supplies air to the upper part of the light emission portion of the projector installed in various positions (including normal position, suspended position, upward projection position, and downward projection position) for prolongation of the life of the arc tube (for example, see JP-A-2010-78973).
According to the projector disclosed in JP-A-2010-78973, a front glass made of transparent material is provided in the front side of the reflection mirror in the light emission direction.
Besides, an air guide member is disposed between the reflection mirror and the front glass. This air guide member has a cylindrical shape surrounding the arc tube, so that air delivered from a cooling fan can flow in a direction along the circumference of the cylindrical shape of the air guide member.
The air guide member has four openings formed at upper, lower, left, and right positions on the air guide member with respect to a center line of the arc tube (optical axis of light emitted from the light source device) as viewed in the direction of the center line. The four openings of the air guide member are openings through which the air guided by the air guide member is supplied toward the upper part of the light emission portion.
The air guide member includes a plurality of valves movable by their own weights.
These plural valves guide air toward the opening located at the upper position with respect to the center line of the arc tube in accordance with the position of the projector so as to supply air toward the upper part of the arc tube through the corresponding opening.
According to this type of light source device, air heated by the light emission portion and the like needs to be discharged to the outside of the space where the arc tube is disposed (space defined by the reflection mirror, the front glass, and the air guide member) for elongation of the life of the arc tube.
For this purpose, according to the projector disclosed in JP-A-2010-78973, an air outlet port is formed in an area of the air guide member where channels for guiding air toward the respective openings are not provided, through which port the air heated by the light emission portion and the like is discharged to the outside.
However, the channels provided inside the air guide member extend substantially throughout the area of the air guide member in the circumferential direction of the cylindrical shape to guide air toward the respective openings formed at the four positions.
In this arrangement, the air guide member has only a limited space which can be opened as the air outlet port.
Accordingly, in the case of the projector disclosed in JP-A-2010-78973, the air heated by the light emission portion and the like easily remains in the space where the arc tube is disposed due to the small opening area of the air outlet port, in which condition prolongation of the life of the arc tube cannot be sufficiently achieved.